ARCHIVED REPORTS_XR0005218 - Laserfiche WebLink

Home Browse Search

' 5.2 Lithology Subsurface conditions interpreted at the site are based on the findings of the scope of services performed by Park on September 1, 21 3 and 29, 1992 and a review of earlier site assessment reports Specific soils encountered from the ground surface to the total depths drilled varied ' from boring to boring even though the site is flat The site is generally underlain with moist hard silt mixtures with several lenses of fine grain sand Some of the mixtures noted were clayey silt, fine sandy silt and clayey fine sandy silt Strong brown, reddish brown and grayish brown, were the dominant colors of the soils encountered in each of the borings. Detailed descriptions of soils encountered in each of the four soil borings are included on the soil bonng logs included in Appendix B Soils were described using the USCS classification which is presented in Appendix B i 5.3 Groundwater Conditions Historically, groundwater has been reported as shallow as 46 5 feet bgs (Pacific Environmental Group, Inc report dated March 16, 1987) Wet soils were encountered in three of the four soil borings drilled by Park at a depth of approximately 75 feet bgs Static ground water levels in MW-1-P, MW-2-P and MW-3-P were measured on September 29, 1992, October 9+, 1992 and October 23, 1992 and were noted between 75 11 feet and 76 79 feet bgs Depth to groundwater ' measurements on September 29, 1992, were collected prior to well development procedures Groundwater flow direction calculations from data collected on that day indicated that groundwater flow is to the south southeast (Figure 3 of Appendix A) On the two subsequent dates, depth to groundwater measurements indicated that groundwater was flowing to the northeast ' Previous reports reviewed by Park indicated the regional and local groundwater flow direction is to the northwest Based on Park's groundwater measurements it appears that a local anomaly may be present and the groundwater is flowing to the northeast with a hydraulic gradient of approximately 0 003 or 0 3 feet per 100 feet Figures 4 and 5 in Appendix A present a graphic illustration of the data obtained from October 9 and 23, 1992 groundwater measuring dates ' During the period of study (March, 1987 to October, 1992) groundwater has declined approximately 30 feet No free product was found during this investigation I 5.4 Results of Soil Sample Analyses Laboratory soil test results are summarized in Table IV Laboratory reports and chain of rcustody documents, including a list of all soil samples collected are provided in Appendix D B 112511 RPT 11 I